All over the world, air quality is getting worse – and especially in the big cities. As a result, air pollution in our homes is also increasing, but in Oslo, where I live, the city council has managed to buck this trend in the last few years – by investing in public transport and pedestrianizing streets where people can move about in green surroundings. Yet despite the city’s best efforts, the air in Oslo is still harmful and there’s more to be done. Those of us who live in towns and cities can do our bit for public health by keeping houseplants in our homes and maybe even a plant or two in the workplace because, in spite of everything, many of us spend about 90 per cent of our time indoors.